Vacuum tube



Jan. 5, 1932'. R. G. BERTHOLD I 1,839,863

VACUUM TUBE Filed June 2:, i925 WITNESSES: I INVENTOR fiuaa/f 6 fierf/fo/d I '25 may be heated in an i Patented Jan. 5, 1932 UNITED STATES PATENT. OFFICE' BUDOLF G. IBEBTHOLD, Oi BEBLIN-SIIMENSSTAD'I, GERMANY, ASSIGNOR '10 WESTING- vnma vacuum rune Application filed June 23, 1925, Serial- No. 38,962, and in Germany July 26, 1924.

This invention relates to vacuum tube devices. Particularly, the invention relates- It is another object of this invention toprovide such an arrangement that the face of the cathode which is thus heated is toward the anode. y

g It is a further object of this invention to provide a cathode of large-thermal capacity and relatively small thermal conductivity and which is heated at only a small portion of the surface.

It is a still further object of this invention to provide an arrangement in which a portion of the cathode maybe heated to or beyond the melting point without destroying the cathode.

Any suitable material may be employed for the cathode, for instance, tungsten. It suitable manner as, for instance, by a bom ardznent-thereof with electrons from a second source.

One form of device embodying the invention is illustrated in the drawing. The single figlure of the drawing is a vertical'sec-- tion t rough the device showing, in a partiall diagrammatic way, the arrangement of t e several parts.

The main-source of electrons is a cathode 1, of conical shape located opposite the anode 2. A plate battery 3 is shown in the drawmg in order to indicate that the electrode 2 is the anode and the electrode 1 is the cathode. The anode has the form of a large bell having a horizontal base.

A second electron source 4 is located on a potential difference between the source 4.

and the cathode 1 isindicated in the drawing by the battery 6. The heating of the electrode 4 is indicated on the drawing by the battery 7 Any other source of heating current may, however, be used.

If the central portion of the surface 5 is heated to such adegree that it softens or even melts, no damage-will result, as the cooler rim portion maintains the softer or fluid central portion in its proper operative position. The heating may even be carried far enough-to melt the central portion of the surface 5, in order to provide as many electrons as possible. i

The heated surface is not necessarily located in a horizontal position, but, if it is not,

the heating may not be carried to the melting point, but only so far that the bombarded portion of the surface becomes softened only. It may be heated until the surrounding cooler portions just suffice to retain it. Tungsten is'well adapted for such purpose.

A art of the surface may be permitted to me t, even when the cathode surface is not horizontal, if the electrode is continuously rotated during use around an axis that is .preferably at an angle of 90 degrees to the glowing surface. The molten material is thereby prevented from dropping off. The electrons from the source 4 are guided by suitable means such as blinders or other cover .members, illustrated by the member 8 havceding detailed description is not intended.

as a limitation. What I desire to protect by Letters Patent is indicated by the following claim.

I claim as my invention:

, An electron-discharge tube comprising a cathode .at one end thereof a means for generating electrons 'at the other end thereof, a hollow anode next adjacent said cathode to receive secondary electrons emitted by said cathode, and an independent shield next adjacent said generating means and having a perforation 1n alignment with said cathode and said generating means for the passage of primary electrons to said cathode.

In testimony whereof, I have hereunto subscribed my name this 29th day of Ma 1925.

vRUDOLF G. BERTH LD.

Inn 

